Web tension control system



Jude 7, 1955 w. BAUMRUCKER, JR., ETAL WEB TENSION CONTROL SYSTEM 4 Sheets-Sheet 1 Filed March -11, 1954 INVENTORS WILLIAM BAUMRUCKER JR. &

CLARENCE M. FLINT BY M ATTORNEY ,June 7, 1955 w; BAUMRUCKER, 1 R., ETAL 2,710,153

WEB TENSION CONTROL SYSTEM Filed March 1 1, 1954 V 4 Sheets-Sheet 2 N M I oooo oooooooob I I n I K' i. I 0 HI l 0 I I p o F INVENTORS o I WILLIAM BAUMRUCKER JR.

" 7 a CLARENCE M. FLINT g BY 7 .m & 7M

ATTORNEY June 7, 1955 w. BAUMRUCKER, JR.. ETAL 2,710,153

was TENSION CONTROL SYSTEM Filed March 11, 1954. 4 Sheets-Sheet 3 N 5 g I a g 2 m 8 58 N 1 L,

o I R s 5 o INVENTORS WILLIAM BAUMRUCKER JR.

& CLARENCE M. FLINT ATTORNEY June 7, 1955 w. BAUMRUCKER, JR., ETAL i 5 WEB 'TENSION common SYSTEM Filed March 11, .1954 4 Sheets-Sheet 4 ll 1 4o 235 224 aws all INVENTORS WILLIAM BAUMRUCKER JR. 2. CLARENCE M. FLINT BY M ATTORNEY United States Patent WEB TENSION CONTROL SYSTEM William Baumruclter, .ln, Reading, Mass., and Clarence M. Flint, Chappaqua, N. Y., assignors to Research Corporation, New York, N. Y., a corporation of New Application March 11, 1954, Serial No. 415,508

Claims. (Cl. 242-75) This invention relates to a web tension control system wherein the tension in a web as it is unwound from a roll is independent of the web tension thereafter, and wherein the tension in the web as it is wound upon a roll is independent of the tension in the Web prior to the winding step.

It is a principal object of the invention to provide Web tension control means for web processing apparatus wherein the tension in the web as it is wound or unwound from a roll or the like is independent of the web tension before or after entering or leaving the web tension control system whereby variations comprised of both low and high frequencyvalues of tension changes, and having a wide degree of amplitude, will not be transmitted to or from the web roll.

"A further object is to provide such a control system wherein it is possible to maintain tension in the web within precisely controlled limits.

A further object is to provide a web tension control system that will substantially obviate web breaks whenrunning or winding out of round rolls.

Another object is to provide a web tension control arrangement that is comparatively simple as to its parts, inexpensive to manufacture, less complex to install and maintain, and readily adaptable to various operatingcon ditions.

The system of the invention may be advantageously employed in a wide variety of industries and with many types of products, for example, textile and plastic weaving, finishing and dyeing, and paper printing, finishing and drying. i

The invention will be more particularly described by way of example with reference to a web printing machine.

Generally, on web-fed printing presses, provision is made for the application of tension on the web roll so that the web of paper leaves the unwinding roll in a taut condition, thus preventing the web of paper from fluttering or weaving and to provide for the control of the web as it enters the printing couple. This tension is often as high as l to 2 pounds per inch of width of the web and means must be provided whereby the press operator may change the tension on the web entering the printing press so that various webs being joined at the folder following printing will be in page register.

' In the past web tension has customarily been applied by braking the unwinding roll, for exam'ple, by providing brake drums on the web roll shafts; or through the use of friction straps which bear against the outside of the-roll; or through the use of a running belt in contact with the periphery of the roll, the belt being driven at a slower speed than the corresponding surface speed of the press web as it is printed.

" Inall of the aforementioned web tension systems, the

web leaves the roll at substantially full operating tension and means for maintaining uniformity of tension and for absorbing slight abrupt tension variations generally comprise a floating roller, over which the web passes prior to its entry into the printing couple. The floating roller g 10 as it. unwinds, idler pulley 20 is supported movablyf Patented June 7,1955

must be sturdy and of heavy construction as the webpassing over it may be at a tension of from about 32 pounds to about 250 pounds, with a normal operating average of about pounds, thus the rollers natural period is long and it is generally provided with hydraulic or the like damping mechanism. The combination of the heavy weight and long period, plus the damping, effectively prevents presently available floating rollers from following rapid fluctuations in the web tension such as those caused by out of round rolls. Thus when eccentric rolls are run at high speed, the web is jerked severely every time a change from the short to the long radius occurs. Even when the roll is only moderately out of round, a jerk as above described occurring simultaneously with the presence of a defect in the web leaving the roll, for example, a slime hole, mill calender cut, or the like, will cause the web to break.

Our web tension control system for a web processing device generally includes a web roll, a web roll drive, drag means between the web roll and the processing device maintaining a controlled tension between said drag means and the processing device, slack gathering means between the web roll and said drag means to smooth out short term variations in the tension of the web and maintaining a predetermined drag on the web at said slack gathering means, means actuated by variations in tension in said web between slack gathering means and the drag means to vary the speed of the web roll drive to maintain said tension within a predetermined range and independent of the web tension between the drag means and the processing device.

In the specification and claims of the application, the

term slack is used to denote variations in the length or Serial No. 242,199 filed'August 17, 1951', by'W. F Huck;

- In the drawings:

Fig. 1 is a diagrammaticview in elevation of oneijform" of the web tension control apparatus of the invention;

Fig. 2 is an enlarged sectional end view of the web takeup mechanism shown in Fig. l; Fig. 3 is an enlarged Fig. 2;

Fig. 4 is an enlarged end view of the web tension applying mechanism shown in Fig. 1; Fig. 5 is an enlarged plan view of the device shown inFig. 4; Fig. 6 is a diagrammatic view'in elevation of another form of the web tension control apparatus of memvention; and

Fig. 7 is a diagrammatic view in elevation of a further form of the web tension control apparatus of the frames of the mechanism but not shown in thedraywings for clarity of the principal components of the invention.

of the outer face of the driving belt 14 contacts with a portionof the periphery of the roll 10. In order to compensate for the normal change in diameterv ofv roll plan view of the device shown in The roll 10 is driven by at least one drivingbelt 14. I The driving belt-passes over a driven pulley 16 and over two idler pulleys 18 and 20 so that a portionin the direction of the arrows and biased toward the roll whereby the drive belt 14 is always in contact with a portion of the periphery of the roll and at constant pressure.

Pulley 16 is drivably secured to a V-belt pulley 22, the latter driven by a .'-belt 24 which in turn is driven by a variable diameter speed changing drive puiley 26. Pulley 26 is secured to a shaft 28 of which one end is driven by a pair of bevel gears 30, one of said gears being secured to a vertical drive shaft 32. The drive shaft 32 is driven by a motor, not shown in the draw" ings. It has been found to be advantageous when employing the device with printing machines to drive the shaft 32 by the same motor that drives the printing couples of the printing machine, whereby, if the printing machine is stopped, started, accelerated or decelerated, the shaft 32 and pulley 26 are likewise actuated.

A bellcrank 34-pivotally mounted on shaft 36 has a floating roller 38 and biasing springs 40 on one arm and an idler pulley 42 which engages the inner surface of V- belt 24 rotatably supported on the other arm. Variations in the. tensions of the web as it passes under floating roller 38 cause slight movements of the bellcrank 34. The movements of the bellcrankcause the idler pulley 42 to change the tension of the V-belt 24 with the result that the V-belt 24 will runon either a larger or smaller diameter of the variable diameter V-belt pulley 26. This effectively increases or decreases the peripheral speed of the driving belt 14 and in turn the peripheral speed of the web, of paper, thus providing the initial control of the speed of the web. This arrangement, however, does not effectively compensate for the fluctuations and jerks in the web occasioned by out-of-round or distorted rolls with the aforementioned roll drive mechanism.

As the" web is unwound by the running belt, it passes over a standard pipe roller 44 thence into a loop. The loop may be maintained by any of the well known methods, for example, a light spring roller or bar, or a roller or bar held against the web by a constant air blast systern, or a soft blast of air alone may be used. In the preferred form of the invention, however, the loop is formed and maintained by a vacuum box 46.

The. vacuum box 46, as more clearly shown in Figs. 2 and 3 of the drawings, generally comprises an elongated trough-like lower portion 48 and an elongated U- shaped cover plate 50 with smoothly down-curved lateral edges; The length of the trough and cover plate is slightly'longer than the maximum width of the web to be used on the particular printing machine. In one of the side or end walls of trough 48 an orifice 52 is provided into which the vacuum conduit 54 is secured. The conduit is preferably provided with a control valve, such as the hand valve 56 shown inthe drawings, for regulating the pull on the Web.

Centrally disposed in the longitudinal axis of the cover plate are a plurality of orifices 58, which function to hold the Web in a loop when a light vacuum is applied to the conduit 54. Fluctuations in the web feed, such as might be caused by out-of-round rolls cause the loop formed and maintained by the vacuum box, to raise and lower thus substantially eliminating web jerks beyond this point. Thusthe web is kept from fluttering or weaving automatically with substantially little tension in the web whereby breakage in the printing material is substantially eliminated at this point.

The web upon leaving the loop passes over a pipe roller 60 antl' then under the floating roller 38, as hereinbefore described. The Web after leaving the floating roller and before entering the tension device may advant'ageously pass to a tension indicator. In the drawings this indicator comprises'fixed' pipe rollers 62 and 64 and a-piperoller 66'rotatably carried by a lever'arm 68 pivotally secured at one end to the main frameof the printingmacbine'. The other-end of lever arm 68 is provided biasing-springs 70' and an indicator pointer; Ad

jacent this pointed end there is a calibrated scale 72 whereby the press operator may at any time ascertain the tension in the web prior to its entry into the primary tensioning device.

Following the tension indicator the web enters a drag means whereby the web is placed under any desired tension within wide limits, for example, to the correct tension to insure accurate printing register, and correct page register at the folder following the printing couple, when the web tension control system is employed on a web printing machine.

In the form of the invention shown in Fig. l of the illustrative embodiments of the invention thedrag means is in the form of a suction box 74. Suction box 74, as is more clearly shown in Figs. 4 and 5 of the drawings, generally comprises an elongated trough-like lower portion 76 and an elongated cover plate 78 with smoothly down-curved lateral edges. The length of the trough and cover plate is slightly longer than the maximum width of the web to be used on the printing machine. In one. of the side or end walls of the trough 76 an orifice 80 is provided into which the vacuum conduit 82 is secured. The vacuum conduit is provided with a control valve such as shown at 84 whereby the press operator may change the suction in the vacuum box to control the drag on the web between the suction box and theprinting couple.

The cover plate is provided with a polished upper surface to reduce frictional drag between the web and the box. In the cover plate one or more narrow slots 86 in the shape of \ls are provided, the apex of the slot being directed opposite to the direction of web travel as shown by the arrows on Fig. 5 with the legs of the slot extending substantially the entire width of the suction box.

As the web is drawn across this suction box by the printing couple of the printing press, the atmospheric pressure tends to hold the web to the upper surface of the cover plate '78 and creates a tension in the web proportional to the suction applied to the box 74. The ii-shaped opening in the cover plate, in addition to tensioning the Web, tends to hold or stretch the web sideways smoothing it prior to its entry into the printing couple. It will be evident that other shaped openings may be used in the cover plate, either alone or in conjunction with the V-slot 36 without substantially altering the primary function of the suction box 74.

Other drag means may be used in place of suction box 74 in the web tensioning system of the invention, for

example a conventional in-feed roller couple geared to the press drive through a variable speed connector may bev used.

Another form of drag means will be described with. In view of the reference to Fig. 6v of the drawings. similarity of the apparatus like parts shown in Figs. 1. through 5 are given double primed numeral designations in Fig. 6.

In Fig. 6 the web originates from a web supply roll 16", driven by at least one driving belt 14". The driving belt passes over a driven pulley 2% and over two idler pulleys 18" and 29" so that a portion of the outer face of the driving belt 14'" registers with a portion of the periphery of the roll 18'. In order to compensate for the normal changein diameter of roll 10" as it unwinds, idler pulley 20 is supported movably in the direction of the arrows and biased toward the roll 14)", for example, by air cylinders not shown in the drawings, whereby the drive belt 14" is always in contact with a portion ofthe periphery of. the roll at a constant pressure.

Drive pulley 200 is secured to a shaft 210 of which one end 'is' driven. by a pair ofbevel gears 212, one of said gears being secured to a vertical drive shaft 214.

The drive shaft'2l4 is the output shaft from the variable speed transmission shown diagrammatically in the draw-- ings at 216. A power input shaft 218 for the variable speed transmission 216 maybe connected to its own-- prime mover or connected to the motor, not shown in the drawings, that drives the printing couples of the printing machine, whereby, if the printing machine is stopped, started, accelerated or decelerated, the input shaft 218 of the transmission 216 is likewise actuated.

The transmission 216 may be any of the well known electrical, mechanical or hydraulic variable speed transmission whereby the torque-speed ratio of the output shaft 214 may be varied relative to the torque-speed ratio of the input shaft 218.

The variable speed transmission 216 is provided with a hydraulic control unit 220 which as shown in the drawings is connected to the transmission by pressure fluid conduits 222. It is evident, however, that the control unit 220 may be of the servoelectric type, for example, and the conduits 222 may be replaced by mechanical linkages or electrical conductors.

A bellcrank 224 pivotally mounted on shaft 236 has a floating roller 38" and biasing springs 40" on one arm and control rod 228 which actuates the control unit 220 pivotally secured to the other arm. Variations in the tension of the web as it passes under the floating roller 38" actuates the control unit 220 through control rod 228. The variations thus produced in the control unit setting are transmitted by means of conduits 222 to the transmission 216 which increases or decreases the speed of output shaft 214. This effectively increases or decreases the speed of drive pulley 200, the peripheral speed of the driving belt 14" and in turn the peripheral speed of the web. This arrangement, however, does not compensate for the fluctuations and jerks in the web occasioned by out-of-round or distorted rolls with the aforementioned roll drive mechanism.

As the web is unwound by the running belt, it passes over a standard pipe roller 44" thence into a loop. The loop may be maintained by any of the well known methods, for example, a light spring roller or bar, or a roller or bar held against the web by a constant air blast systern, or a soft blast of air alone may be used. In the preferred form of the invention, however, the loop is formed and maintained by a vacuum box 46".

The vacuum box 46" is substantially as shown and described with reference to Figs. 2 and 3 of the drawings and generally comprises an elongated trough-like lower portion 48 and an elongated U-shaped cover plate 50" with smoothly down-curved lateral edges. The length of the trough and cover plate is slightly longer than the maximum width of the web to be used on the particular printing machine. In one of the side or end walls of trough 48 an orifice 52" is provided into which the vacuum conduit 54 is secured. The conduit is preferably provided with a control valve, such as the hand valve 56 shown in the drawings, for regulating the pull on the web.

Centrally disposed in the longitudinal axis of the cover plate are a plurality of orifices, which function to hold the web in a loop when a light vacuum is applied to the conduit 54". Fluctuations in the web feed, such as might be caused by out-of-round rolls cause the loop formed and maintained by the vacuum box, to raise and lower with substantially no jerks in the web. Thus the web is kept from fluttering or weaving automatically with substantially little tension in the web whereby breakage in the printing material is substantially eliminated at this point.

The web after leaving the loop forming device passes over a pipe roller 60", then under floating roller 38" and over and under standard pipe rollers 98" thence to a drag means generally designated 240. The drag means 240 comprises a flat plate 242 of metal or the like having a width slightly greater than the width of the web. Positioned above the plate 242 are one or more conduits 244, the longitudinal axis of which preferably lies across the width of the plate 242. Each of the conduits 244 is supplied with compressed air or the like through conduits 246 which in. turn are connected to a suitable, sourceof the pressure fluid. A plurality of pressure fluidfoutlet's' j' 248 are provided in the conduits 244 adjacent the upper surface of plate 242 through which jets or streams f of air issue. The force of the air stream causes a friction drag between the travelling web and the upper surface of the plate 242. The amount of tension to be applied to the web is dependent on the magnitude of the pressure applied by the air stream and the surface texture of the plate 242. A manual or automatic valve 250 may be provided in each conduit 246 whereby control of the drag means may be readily had.

In Fig. 7 of the drawings a further form'of the invenQ In this form of the ,apparatus only the tion is shown. means for sensing the tension in the web between the web roll and the drag means and the control means responsive to the sensing means for varying the speed of the web roll drive will be described as the other elements thereof are identical in structure and function to those shown and described in reference to Fig. 1. identical reference numerals are, therefore, provided on"'the web roll 10, pipe rollers 40 and 60, slack gathering means 46, and drag means 74. After the web leavesthe slack gathering means 46 where a predetermined light drag is applied to the web, it passes under a balanced floating roller 270 rotatably mounted at one end of lever 272. The lever 272 is mounted for up and down pivotal movement at 274 and connected at its other end to link rod 276 which is pivotally connected to a second lever 278 also mounted for up and down pivotal movement at 280. Lever 278 is connected to the piston of an air cylinder generally designated 282 provided with valves 284 for initially adjusting the system for the slack or tension in the web. The springs 286 and 286 are balancing springs to compensate for the weight of the levers 272 and 280 and their connected elements.

Pivotal movement in lever 278 brought about by variations in the slack or tension in the web as it passes under roller 270 is transmitted to rods 288 and 290 which are connected to valves 292 and 294 respectively. These valves control the flow of pressure fluid to a pressure fluid actuated control motor generally designated 296. The control motor 296 is connected through mechanical linkages 298 and 300 to a conventional speed changer 302. The speed changer 302 mechanically moves the movable sheave of the adjustable pulley 304 of the web drive generally designated 306 through shaft 308. As the movable sheave of the adjustable pulley 304 moves in or out as the case may be, its effective diameter and the resultant speed of the web roll driving belts are varied.

The drag means 240 in Fig. 6 may be advantageously replaced by the suction box 74 shown in Figs. 1 and 7 of the drawings or by in-feed rolls.

From the foregoing description it will be seen that the present invention provides an improved web tensioning system whereby the aims, objects and advantages of the invention are fully accomplished. It will be evident that while the present invention has been described in reference to web roll unwinding apparatus, it will be apparent that the objects and advantages of the system may be fully realized on Web roll winding machines.

This application is a continuation-in-part of our application Serial No. 290,668 filed May 29, 1952, now abandoned.

We claim:

1. A web tension control system for a web processing device including a web roll, and a web roll drive, comprising drag means between the web roll and the processing device maintaining a controlled tension between said drag means and the processing device, slack gathering means between the web roll and said drag means to smooth out short term variations in the tension of the web and maintaining a predetermined drag on the web at said slack gathering means, means actuated by variations in tension in said web between the slack gathering 7 means and the drag, means tov vary the speed of the web roll drive to'rnaintainsaid tension within a predetermined range and independent of the web tension between the dragmeans and'the processing device.

2. A web tension control system for a web processing device as defined in claim 1' whereinsaid slack gathering means comprises a suction box, means for applying a negative pressure to said box, a concave cover plate secured to said box having openings therein communicating with the'interior of'the box and one face of the web.

3'. A 'web tension control system as defined in claim 2 wherein saiddrag means comprises a second suction box, means'for applying a negative pressure to said second box, aisubstantially fiat cover plate'secured to the top of said second box and having openings therein communicati'ngwith the interior of the box and one face of the web.

'4. A web tension control system for a web processing device including a web. roll, and a web roll drive, compris ing drag. means between the web roll and the processing device maintaining a controlled tension between said drag means and the processing device, slack gathering means between the web roll and said drag means to smooth out 8;: short term variations'in the tension of the web and maintaining a predetermined drag on the web at said slack gathering means, means for sensing the tension of said web between the slack gathering device and the drag means, means responsive to said sensing means for varying the speed of the web roll drive to maintain the tension of the web between the web roll and said drag means within a predetermined range and independent of the web tension between the drag means and the processing device. 5. The invention defined in claim 4 wherein the means for sensing the tension of the web comprises a balanced floating roller.

References Cited in the file of this patent UNITED STATES PATENTS 1,263,419 James Apr. 23, 1918 2,203,014 Freeman June 4, 1940 2,218,548 I Pangerl Oct. 22, 1940 FOREIGN PATENTS 165,510 Switzerland Mar. 1, 1934 

